1. Field of the Invention
The present invention relates to a computer room reduced air flow method and assembly but is not limited to use in computer rooms and instead can be utilized with respect to any equipment assembly requiring cooling which is positioned in a room. The method and assembly described below permits control of the flow of cooling air within equipment assembly and achieving energy savings while reducing the amount of air required to cool electronic/heat generating equipment, where a computer rack heat extraction device (CRHED) or similar device such as a custom air handling unit (AHU) is utilized. The method and apparatus permits the collection of heat generated, for example, by the rack electronic equipment.
2. Discussion of the Background
The conventional computer room method and assembly illustrated in FIG. 1 exemplifies the approach for cooling electronic equipment commonly used currently wherein an array of racks of equipment are positioned on a raised floor. FIG. 1 illustrates an air conditioning system used in the method and apparatus of a conventional system wherein a room space 1 defined by a room floor, sidewalls 3 and a ceiling 4 having a plurality of ceiling panels is provided. The room floor 2 is positioned a predetermined distance above a base floor 5 such that the room floor 2 and the base floor 5 in combination form a double floor structure having a free space 6 (i.e. air passageway) formed therein. A rack 7 for one or more computer processing units (CPU) is disposed on the floor 2 wherein electronic cables for the rack are capable of being housed in the free space 6 of the double floor structure but can be specifically communicated to the rack separate from the free air space if desired.
In installing each of the CPUs or other equipment on the rack on the floor, a plurality of support members can be provided which are stationary by being fixed by bolts or similar fastening elements to predetermined positions on the floor 2.
The rack 7 is positioned in a casing 8 having air inlets 8a and air outlets 8b formed respectively in a bottom plate of the casing 8 and in the ceiling portion of the casing 8. A computer case fan 9 is operable during operation of the equipment 7 so as to assist the air flow upwardly from the casing through the air outlets 8b. As shown in FIG. 1, the CPU members are arranged in an air passageway formed within the casing 8. The floor 2 includes a plurality of floor panels located on pedestals 2b, one panel 2a of which includes a plurality perforations to allow air flow as indicated by the arrows to freely flow without control through the front of the outside housing of casing 8, through the CPU rack 7 and out the back passageway or cavity of casing 8. A cooling unit 14 is positionable either inside or outside the room 1 and is communicated with a heat exchanger or other air conditioning equipment so as to permit a cooling coil 15 located within unit 14 to cool air blowing therethrough. The cooling unit 14 also includes a fan 16 which is positionable below cooling coil 15. An inlet 20 is provided to allow air from the room to flow thereinto from the room, the air in the casing 8 mixing with room air prior to being introduced into the cooling unit 14, as illustrated in FIG. 1. The fan 16 is therefore arranged between the air inlet 20 and an air outlet 22 located at the lower portion of unit 14 and feeds air into the free space 6 located above the base floor 5. The fan 16 thus permits air in the interior of the room to be sucked into the air inlet 20 of the casing 8 and also permits the air in the room to pass through cooling coil 15. The air in the room is typically at a temperature of 75xc2x0 F.xc2x1.
The above-noted approach for cooling electronic equipment thus permits the area in the free space 6 below the raised floor 2 to be used for cable management and also serve as a supply air plenum. The computer room air conditioning units (CRACUs) utilize cooling coil 15 to cool the air. The CRACUs supply conditioned air at approximately 55xc2x0 F. to the under floor supply air plenum or free space 6. Floor tiles with perforations or slots to allow air to flow from under the raised floor to above the floor are positionable below or are adjacent to the rack 7. Other perforated tiles are positioned throughout the room to provide air supply to other heat generating equipment and to maintain the room in an ambient environment.
As illustrated by the arrows in FIG. 1 showing the air flow, the conditioned air is then drawn into the rack 7 by either convection by air flow from perforated panels 2a into the casing 8 or by fans 9 located in the top of the racks. The air enters the racks at a temperature of approximately 55xc2x0 F., is heated by the CPUs or other electronics, and flows upwardly out of the rack at approximately a temperature of 95xc2x0 F. The warm air leaves the rack and mixes with the conditioned ambient environment of the room 1 which is at a temperature of approximately 75xc2x0 F., and thus returns to the CRACU""s at a temperature of approximately 75xc2x0 F. as illustrated in FIG. 1.
In view of the foregoing, it can be understood that conventional CRACU""s have a 20xc2x0 delta T (+ or xe2x88x924xc2x0 F.) across the cooling coil 15. This is also coincident with the space delta T which is defined as being the difference in temperature between the air supplied to the space, and the air returned from such space. The temperature of the air returned from the space is usually coincident with the ambient space temperature such that the return air at 75xc2x0 F. enters the return on top of the CRACU""s, passes across the cooling coil 15 and is discharged at a temperature of substantially 55xc2x0 F. at the bottom of unit 14 so as to pass into the free space 6. The required air quantity to cool such space is a direct function of the space delta T. The equation set forth below is used to calculate the required air flow or cubic feet per minute (CFM) of air to cool a space:
CFM=BTUH/1.08xc3x97delta T 
From the foregoing, it can be appreciated that the disadvantage of the conventional system set forth above requires a significant amount of fan horsepower for operation and thus the need has arisen for reducing the amount of horsepower necessary to operate the fan 16. In addition, the flow of cooling air across the rack is uncontrolled so as to not necessarily adequately cool each equipment member in the rack 7.
The devices of the type described above are exemplified by, for example, by U.S. Pat. No. 5,718,628; U.S. Pat. No. 4,774,631 and U.S. Pat. No. 5,910,045, the disclosure of each of which is herein incorporated by reference, as is the disclosure of provisional application Nos. 60/289,787 and 60/289,786, the priority of each is claimed in the present application.
One object of the present invention is to provide a flow control device upstream and downstream of the rack so as to effectively and uniformly cool each item of equipment of the rack.
An additional object of the present invention is to provide a method and apparatus which utilizes an increased delta T to reduce their required air quantity, thus resulting in a reduced airflow method and apparatus. Specifically, the present invention utilizes approximately 40xc2x0 F. delta T to reduce the CFM by substantially 50%. The substantially 50% reduction in the airflow will serve to effectively correspondingly reduce the required power by substantially 50%, resulting in substantial energy savings. A key element of the method and apparatus is an increase in delta T above what is conventionally used. The present invention is capable of operating in a range of delta T from 25xc2x0 F. to 45xc2x0 F. In this regard, it is noted that the use of a 40xc2x0 F. in the description set forth below is solely exemplary in illustrating device and greater or lesser temperature variations are possible.
An object of at least one embodiment of the present invention is to provide an air conditioning method and apparatus which utilizes the steps of supplying cooling air generated from a cooling apparatus into an air passageway formed below a floor; guiding the cooling air within the air passageway into an equipment assembly disposed on the floor through an opening located in the floor; communicating the cooling air introduced into the equipment assembly into a plenum and introducing the air released from within the equipment into the plenum for communicating such released air to the cooling apparatus. The method may also include the step of guiding the air from the equipment assembly through at least one duct into the plenum and may include the step of cooling the cooling air generated from the cooling apparatus to a temperature of substantially 55xc2x0 F. while also heating the air released from the equipment assembly to a temperature of substantially 95xc2x0 F. prior to introducing such air to the cooling apparatus so as to form a closed loop in terms of cycling of the air through the cooling assembly and the equipment assembly.
A further object of the present invention is to obtain a temperature differential between the air supplied to the air passageway or plenum from the cooling apparatus and the air introduced into the plenum from the equipment assembly so as to be substantially 40xc2x0 F., thus permitting lower power requirements of the fan utilized to assist flow of the air in the closed loop.
A further object of the present invention is to position the fan between the cooling apparatus and the air passageway so as to permit blowing of the air into the passageway towards the equipment assembly, although it is understood that the fan can be located anywhere within the closed loop so as to assist flow of air between the blowing apparatus and the equipment assembly.
A further object of the present invention is to provide a method and apparatus wherein the cooling assembly is located either within or outside the computer room, the equipment assembly comprising either at least one computer processing unit or other type of processing unit in combination with an additional heat generating equipment or with out such equipment. In addition, a further object of the present invention is to cool equipment assembly generating heat which does or does not include computer equipment.
An additional object of the present invention is to provide an air conditioning assembly for performing the method described above.